The invention concerns rolling screen arrangements of the type comprising a flexible sheet-like element wound on a rod-like windings support which is rotatable for winding and unwinding of the flexible element onto and off of the support, and a tensioning device acting on a trailing end of the flexible element to hold the element under tension.
Such arrangements may be rolling window blinds or shades (which the flexible element is a fabric or a series of articulated laths), projection-screens, rolling garage doors and so forth.
In known tensioning devices for arrangements of this type, such as that described in W. German published Patent Application (DOS) No. 2341328, drums are provided solid for rotation with the winding support. A flexible cord is wound by one end on each drum with a direction of winding opposite to that of the flexible element on the winding support. The other end of each cord, which is held under tension by means of suspended weights and associated guide carriages, is connected to the trailing end of the flexible element so that the flexible element is permanently held at constant tension during winding and unwinding.
Likewise, U.S. Pat. No. 3,279,528 describes an arrangement of the same type in which the flexible element of "shade" is held at constant tension so that it can be stopped at any intermediate position without the need for additional catches or locks.
However, it has been observed that permanently holding the flexible element under tension, even when it is fully or almost fully wound, is unnecessary and disadvantageous in that the inflexible element, its winding support and winding mechanism are constantly subjected to stress.